In a wireless local area network (WLAN), an access point (AP) is a device which is able to communicate wirelessly with one or more stations. A station (STA) is any device that is able to wirelessly receive data from and/or wirelessly transmit data to an access point. In some, but not all, cases stations connected to the WLAN may be able to access the internet via the access point. WLAN may operate according to various protocols and the most common are defined by 802.11 family of standards. Recent developments in WLAN technologies include the introduction of Multiple Input Multiple Output (MIMO) techniques. That is, a radio frequency module for an access point may transmit multiple paths of signals simultaneously and may also simultaneously receive multiple paths of signals, and thus the utilization rate of channels can be raised by space multi-path technologies. Accordingly, one radio frequency module needs multiple antennas, and as for the character of the MIMO techniques, signal quality can be improved through multi-path phenomenon. One example of a WLAN standard that uses MIMO is 802.11n. 802.11n offers greatly increased physical rates, but has relatively restrictive requirements for the antennas' radiation angles and correlations between the antennas. In many conventional access points, one fixed antenna is provided for each signal transmitted or received, and rate selections of different modulation modes are performed to obtain an optimal result at software components.
In practical applications, throughput can be easily changed by rotating an Access Point (AP) or a Station (STA) by a certain angle. Therefore, some AP providers have begun to introduce smart antennas, such those that have been widely used in conventional mobile communications (e.g., 3G, LTE etc.), to a Wireless Local Access Network (WLAN) device, so as to improve WLAN user experiences.